65 mustang starting problems
 

1965 mustang starts at times with the key and at times it will not. Most likely to start after it has been run awhile. Starter not running. Car always starts after jumping the solenoid against the cars frame. Used to start in neutral now not at all.

I would start simply by cleaning all the electrical connections followed by a new solenoid. If that dosen't get it I would bet you have a bad connection between the ignition and the solenoid. But it sounds to me like a poor electrical connection.